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PostPosted: Tue Mar 07, 2017 10:02 pm 
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Another thread on how to remove the cylinder caps of Steyr Cylinders got me to making the wrench and opening 2 of my 5 CO2 cylinders for my Steyr LP1-P, purchased new in 1991.

A lot has been written about how the ALUMINUM cylinders should be discarded after a while because the CO2 causes pitting and corrosion inside the tube. Well, here is a picture of the inside of the Short Alu CO2 cylinder. This cylinder was purchased in 1992, and has held CO2 perfectly, until a month of two ago.

That's 25 years of service...

I have not cleaned this tube in any way. It appears exactly as it did when first opened. Essentially, notice the near mirror finish on the walls of the tube. No pitting, or corrosion of any kind whatsoever. It looks like the day it was assembled, 25+ years before.

In my opinion, all this sky-is-falling talk of dangerous cylinders older than 10 years is BS.


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PostPosted: Wed Mar 08, 2017 12:14 am 
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A CO2 cylinder is only experiencing about 1000 psi where Compressed air PCP cylinders often experience more than 3000psi. Furthermore, there is often moisture condensed in the cylinders that use air. this can have corrosive effects. That being said the anodizing on the inside of the cylinders does provide a layer of protection. However, anodizing is basically a ceramic that will develop micro cracks and fissures with the slight expansion and contraction of the tank going thru pressurization cycles. This can cause an avenue for corrosion. These cycles can also cause metal fatigue and fissures associated with this as well. While I disagree with the blanket policy, I understand and agree with its purpose and intent.

I feel there should be avenues within the rules to allow for nondestructive inspection (NDI) for cylinders and have them recertified. I also wouldn't mind longer inspection or replacement periods for manufacturers that overengineer their cylinders like making them out of titanium and testing them to 300-400% of their rated capacity.

Best Regards,

David Finell


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PostPosted: Wed Mar 08, 2017 3:04 am 
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I have seen inside Air cylinders that have been refilled by scuba and pumps. Almost without exception the Air cylinders filled by scuba showed very little to no corrosion whereas the ones filled by hand pump developed corrosion more quickly and progressed rapidly.

I remember Ulrich Eichstadt ( Walther ) describing some of the cylinder interiors he has seen as resembling minefields the corrosion was so bad.

The interesting point to me was the increased rate of corrosion in cylinders hand pumped versus scuba filled.


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PostPosted: Wed Mar 08, 2017 3:08 am 
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somewhere from a physicist I read that the air pressure causes no cracks, that's why I wrote in that other thread that cylinders are good for hundreds of years. The only problem is corrosion, but the air pressure itself causes no harm to aluminum

there's also no European law for small cylinders limiting their lifetime, only for bigger ones.


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PostPosted: Wed Mar 08, 2017 12:01 pm 
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I suppose it's nice that the ISSF rules still mention CO2 as a permitted propellant for AP/AR.

However, I am not aware of any AP company making any "NEW" CO2 cylinders since the late 90s (just a guess, please let me know if different). Accordingly, I assume a priori that the 10-year rule basically obsoletes CO2 power, since no one has manufactured CO2 cylinders more recently than 2007? Again correct me if I am wrong.

I understand the Olympics want to promote "Green" sports, so ISSF might see it as a way to do away with CO2 without having to do more than observe the passage of time.

Meanwhile, I think I have shown that CO2 has no long term effects on the metallurgy of aluminum cylinders.


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PostPosted: Wed Mar 08, 2017 12:46 pm 
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"I understand the Olympics want to promote "Green" sports, so ISSF might see it as a way to do away with CO2."

Are they really that stupid! CO2 guns don't MAKE CO2, they just recycle it.


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PostPosted: Wed Mar 08, 2017 1:45 pm 
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Rover wrote:
Are they really that stupid! CO2 guns don't MAKE CO2, they just recycle it.

Given a number of decisions they have made in recent years, I think the answer to your question is probably "yes"...


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PostPosted: Wed Mar 08, 2017 2:18 pm 
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Quote:
However, I am not aware of any AP company making any "NEW" CO2 cylinders since the late 90s (just a guess, please let me know if different)


FWB are still producing CO2 cartridges for the FWB C25

http://www.egun.de/market/item.php?id=6159815


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PostPosted: Wed Mar 08, 2017 3:12 pm 
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Rover wrote:
"I understand the Olympics want to promote "Green" sports, so ISSF might see it as a way to do away with CO2."


and lead??


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PostPosted: Wed Mar 08, 2017 5:41 pm 
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Actually, DFWdude wrote it, but I see some clubs won't allow lead pellets OR CO2 already.

Morons!


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PostPosted: Wed Mar 08, 2017 5:49 pm 
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Oh, you fell for it, buddy. The interior of the cylinder was originally a deep matte finish (tiefmatt) which 25 years' worth of CO2 exposure has mirror polished (spiegelpoliert), removing Gawd knows how much material. That cylinder wall will be foil-thin in no time at all.


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PostPosted: Wed Mar 08, 2017 8:57 pm 
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william wrote:
Oh, you fell for it, buddy. The interior of the cylinder was originally a deep matte finish (tiefmatt) which 25 years' worth of CO2 exposure has mirror polished (spiegelpoliert), removing Gawd knows how much material. That cylinder wall will be foil-thin in no time at all.


I do not think so. I opened a steel cylinder today. The steel cylinder and the aluminum cylinder have EXACTLY the SAME wall thickness (.100", or 2.54mm), and EXACTLY the SAME Inside Diameter (.990", or 25.15mm). BTW, the steel cylinder has a dark finish (your tiefmatt, maybe?), as otherwise it would just be raw steel, open to (possible) corrosion... though none visible. But the aluminum does not have a contrasting finish internally.

I have 5 cylinders altogether. The two described had leaks, and indeed the seals were degraded. Once I can acquire a bunch of poly o-rings, I will open the remaining three steel cylinders to reseal all of them together. I'm betting they will all be internally identical, visually.

Finally, those familiar with the CO2 days remember that the only way to monitor CO2 fills was to weigh the cylinders... Full weight minus tare weight = CO2 load All my cylinders have stickers dating to the early 90s with a hand-written tare weight (which seldom matched the stampings on the cylinders) and full weight. On the two cylinders opened so far, the tare weights today are identical to that written on the stickers 25 years ago... meaning there has been ZERO loss of mass in the cylinder materials, meaning ZERO corrosion.

Sorry I don't have any official-sounding German/Austrian verbiage to phrase it with more authority. So I'll just call it horse-pucky, again.


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PostPosted: Wed Mar 08, 2017 10:49 pm 
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DFWdude,

O-rings can be obtained in inexpensive sets at Harbor Freight tools. I used one of these sets to replace the o-ring on my Hammerli fill adaptor. They carry both metric and SAE.

Also, corrosion won't cause a loss of mass in the cylinders. If anything it will cause an increase in mass as the metal oxidizes. The only way the mass would decrease is if the corrosion becomes separated from the host metal. This would most likely lead to gun malfunctions.

CO2 tanks are less prone to oxidation as they are inherently dry. CO2 lacks the moisture which is the primary source of corrosion. There is effectively no H2O.

Best Regards,

David Finell


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PostPosted: Thu Mar 09, 2017 6:40 am 
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DFWdude wrote:
william wrote:
Oh, you fell for it, buddy. The interior of the cylinder was originally a deep matte finish (tiefmatt) which 25 years' worth of CO2 exposure has mirror polished (spiegelpoliert), removing Gawd knows how much material. That cylinder wall will be foil-thin in no time at all.


I do not think so. I opened a steel cylinder today. The steel cylinder and the aluminum cylinder have EXACTLY the SAME wall thickness (.100", or 2.54mm), and EXACTLY the SAME Inside Diameter (.990", or 25.15mm). BTW, the steel cylinder has a dark finish (your tiefmatt, maybe?), as otherwise it would just be raw steel, open to (possible) corrosion... though none visible. But the aluminum does not have a contrasting finish internally.

I have 5 cylinders altogether. The two described had leaks, and indeed the seals were degraded. Once I can acquire a bunch of poly o-rings, I will open the remaining three steel cylinders to reseal all of them together. I'm betting they will all be internally identical, visually.

Finally, those familiar with the CO2 days remember that the only way to monitor CO2 fills was to weigh the cylinders... Full weight minus tare weight = CO2 load All my cylinders have stickers dating to the early 90s with a hand-written tare weight (which seldom matched the stampings on the cylinders) and full weight. On the two cylinders opened so far, the tare weights today are identical to that written on the stickers 25 years ago... meaning there has been ZERO loss of mass in the cylinder materials, meaning ZERO corrosion.

Sorry I don't have any official-sounding German/Austrian verbiage to phrase it with more authority. So I'll just call it horse-pucky, again.

Apparently irony really is dead. And somebody has too much time on his hands.


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PostPosted: Thu Mar 09, 2017 9:19 am 
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Finelld wrote:
DFWdude, O-rings can be obtained in inexpensive sets at Harbor Freight tools. I used one of these sets to replace the o-ring on my Hammerli fill adaptor. They carry both metric and SAE.

Ummmm, the cheap Buna o-rings available at Harbor Freight will blow up to 8-times their size when exposed to CO2. I have 3 Harbor Freights available here in the Dallas area, and will shop there for some items. For o-rings, I drive to H&D Distributors, a 50,000 sq ft operation that supplies industrial o-rings used around the world. The usually have every type of o-ring available, including polyurethane, in both SAE and metric sizes.

Finelld wrote:
Also, corrosion won't cause a loss of mass in the cylinders. If anything it will cause an increase in mass as the metal oxidizes. The only way the mass would decrease is if the corrosion becomes separated from the host metal. This would most likely lead to gun malfunctions.
I'm not a trained metallurgist, but as a machinist of 40 years, I can tell what corrosion is... and will tell anyone open-minded enough to listen that there is ZERO corrosion in these cylinders.

Finelld wrote:
CO2 tanks are less prone to oxidation as they are inherently dry. CO2 lacks the moisture which is the primary source of corrosion. There is effectively no H2O.
Ah, finally.


Last edited by DFWdude on Thu Mar 09, 2017 10:02 am, edited 2 times in total.

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PostPosted: Thu Mar 09, 2017 9:38 am 
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william wrote:
Apparently irony really is dead. And somebody has too much time on his hands.

If your post was a spoof, then you got me.

Unfortunately, there are more than a few people who hear/read spoofs, shadetree science, and pseudo-science disguised as sales hype, that they will read and accept your comments as "fact." Thanks for clarifying. I wish others would be as forth-right.

The purpose of this thread was to dispel some of the myths regarding CO2 cylinders, foisted on us by airgun manufacturers interested in selling us new technologies (new cylinders, AND new airguns)... designed obsolescence propaganda freely accepted by the ISSF, more concerned with liabilities than reality.

I don't consider that time wasted.


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PostPosted: Thu Mar 09, 2017 12:17 pm 
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DFWdude wrote:
For o-rings, I drive to H&D Distributors, a 50,000 sq ft operation that supplies industrial o-rings used around the world. The usually have every type of o-ring available, including polyurethane, in both SAE and metric sizes.


McMaster-Carr (mcmaster.com) has just about any type of O-ring you'd want, without the drive. (For those without a worldwide distributor nearby, you know.)

I don't know about air gun cylinders, but wall thickness between steel and aluminum scuba cylinders is dramatically different. If steel and aluminum air cylinders are the same wall thickness, one is way over-built.

jky


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PostPosted: Thu Mar 09, 2017 1:09 pm 
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Location: Southern New England
I’m much more concerned with the gauge failing catastrophically than I am the cylinder rupturing from metal fatigue; but both are potential failure points.

With the costs of .22’s these days I can easily shoot off the cost of a new air cylinder in a weekend, a new $200 cylinder every ten years is pretty cheap insurance for my safety in the big picture.

Not much about target shooting is inexpensive if you are doing it right. Guns, travel, lodging, time, ammo, entry fees it all adds up fast.


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PostPosted: Thu Mar 09, 2017 9:08 pm 
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Jon Math wrote:
I’m much more concerned with the gauge failing catastrophically than I am the cylinder rupturing from metal fatigue; but both are potential failure points.
I've experienced an air gauge failure on the 200bar air cylinder of an S200 10m rifle. Lots of mild hissing as the cylinder dumps, but no drama otherwise. Certainly no explosion. This rifle cylinder dated to the first days of S200 PCP (late 90's?).

The circular Bourdon tube that flexes to turn the dial developed a loose soldered joint with repeated expansion and contraction. Resealed with a light touch using a soldering iron, and all is well again (years now).


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PostPosted: Fri Mar 10, 2017 7:47 am 
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Thanks, that is good to know. I always wondered if it would just leak or blow off the end of the cylinder.


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